Semiconductor light emitting device

ABSTRACT

A semiconductor light emitting device comprises a first nitride semiconductor layer comprising a plurality of concave portions, a reflector in at least one of the concave portions of the first nitride semiconductor layer, and a second nitride semiconductor layer on the first nitride semiconductor layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. 126 to KoreanPatent Application No. 10-2008-0041200 (filed on May 2, 2008), which ishereby incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a semiconductor light emitting device.

Group III-V nitride semiconductors have been variously applied to anoptical device such as blue and green Light Emitting Diodes (LED), ahigh speed switching device such as a Metal Oxide Semiconductor FieldEffect Transistor (MOSFET), a High Electron Mobility Transistor (HEMT)and a Hetero junction Field Effect Transistor (HFET), and a light sourceof a lighting device or a display device.

The nitride semiconductor is mainly used for an LED or a Laser Diode(LD), and studies have been continuously conducted to improve themanufacturing process or light efficiency of the nitride semiconductor.

SUMMARY

Embodiments provide a semiconductor light emitting device whichcomprises a reflector having a cavity in at least one portion of asemiconductor layer.

Embodiments provide a semiconductor light emitting device whichcomprises a plurality of concave portions and reflectors having aninverse horn shape between a plurality of semiconductor layers.

Embodiments provide a semiconductor light emitting device whichcomprises discontinuous reflectors having a single-layer or multi-layerstructure between a plurality of semiconductor layers.

Embodiments provide a semiconductor light emitting device comprising aplurality of reflectors and cavities which are disposed in a nitridesemiconductor layer under a light emitting structure.

An embodiment provides a semiconductor light emitting device comprising:a first nitride semiconductor layer comprising a plurality of concaveportions; a reflector in at least one of the concave portions of thefirst nitride semiconductor layer; and a second nitride semiconductorlayer on the first nitride semiconductor layer.

An embodiment provides a semiconductor light emitting device comprising:a nitride semiconductor layer comprising a plurality of concaveportions; a plurality of reflectors in the concave portions of thenitride semiconductor layer; a cavity on at least one of the reflectors;and a plurality of compound semiconductor layers on the nitridesemiconductor layer.

An embodiment provides a semiconductor light emitting device comprises:a nitride semiconductor layer comprising a plurality of concave portionshaving a horn shape; a plurality of reflectors having a horn shape inthe concave portions of the nitride semiconductor layer; and a firstconductive semiconductor layer on the nitride semiconductor layer.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side-sectional view of a semiconductor light emitting deviceaccording to a first embodiment.

FIGS. 2 to 13 are diagrams illustrating a process of manufacturing thesemiconductor light emitting device in FIG. 1.

FIG. 14 is a diagram illustrating a semiconductor light emitting deviceaccording to a second embodiment.

FIGS. 15 to 21 are diagrams illustrating a semiconductor light emittingdevice according to a third embodiment.

FIGS. 22 to 28 are diagrams illustrating a process of manufacturing asemiconductor light emitting device according to a fourth embodiment.

FIG. 29 is a side-sectional view of a semiconductor light emittingdevice according to a fifth embodiment.

FIG. 30 is a diagram illustrating a semiconductor light emitting deviceaccording to a sixth embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings. In description of embodiments, each element will be describedas an example and is not limited to the size of the accompanyingdrawings.

FIG. 1 is a side-sectional view of a semiconductor light emitting deviceaccording to a first embodiment.

Referring to FIG. 1, a semiconductor light emitting device 100 accordingto the first embodiment comprises a substrate 101, a nitridesemiconductor layer 110, a plurality of reflectors 120, a firstconductive semiconductor layer 130, an active layer 140, a secondconductive semiconductor layer 150, a first electrode 161, and a secondelectrode 163.

The semiconductor light emitting device 100 comprises a light emittingdiode (LED) based on group III-V compound semiconductors, and the LEDmay comprise a color LED emitting blue light, green light or red lightor an UV LED. The light emitted from the LED may be variously realizedwithin the technical scope of the embodiment.

The substrate 101 may be formed of at least one of sapphire substrate(Al₂O₃), GaN, SiC, ZnO, Si, GaP and GaAs.

An island pattern 105 is formed on the substrate 101. The island pattern105 has an island shape, regular pattern or irregular pattern, and maybe formed at regular intervals or irregular intervals.

The pattern may be formed in a shape of regular shape or irregular shapeby using a photomask material, or may be formed in the island shape byusing the thin film of a compound semiconductor.

The pattern may be formed by selectively using photomask materials suchas SiO₂, SiO_(x), SiN_(x), SiO_(x)N_(y) and metal materials, or may beformed of at least one of compound semiconductor materials such as GaN,InN, AlN, InGaN, AlGaN and InAlGaN. However, the materials may bechanged in the spirit and scope of embodiments.

A buffer layer or/and an undoped semiconductor layer may be formed onthe substrate. The buffer layer or/and the undoped semiconductor layercomprises a group III-V compound semiconductor. The pattern may beformed on the buffer layer or the undoped semiconductor layer.

The nitride semiconductor layer 110 having a certain thickness is formedon the substrate 101.

The nitride semiconductor layer 110 may be formed to have a thicknessthicker than that of the island pattern 105.

The nitride semiconductor layer 110 comprises a group III-V compoundsemiconductor, for example, may be selected from the group consisting ofGaN, InN, AlN, InGaN, AlGaN and InAlGaN. The nitride semiconductor layer110 may be a semiconductor layer on which a conductive dopant is dopedor an undoped semiconductor layer on which the conductive dopant is notdoped.

The upper portion of the nitride semiconductor layer 110 comprises aplurality of concave portions 112 and convex portions 113. The concaveportions 112 are formed in a position corresponding to the islandpattern 105. The convex portions 113 are formed in a flat plane atregions other than the concave portions 112.

The concave portion 112 of the nitride semiconductor layer 110 may beformed in at least one of an inverse pyramid shape, an inversemulti-angle horn shape, an inverse cone shape and an inverse multi-angletruncated-horn shape. Moreover, at least one side of the concave portion112 may be slopingly formed. In embodiments, the shape of the concaveportion 112 will exemplify an inverse horn shape as an example. However,such a shape may be modified in the spirit and scope of embodiments.

The concave portions 112 of the nitride semiconductor layer 110 may beformed in a conformal or non-conformal shape, but is not limitedthereto.

The reflector 120 is formed on the concave portion 112 of the nitridesemiconductor layer 110. The reflector 120 may be formed on aconcave-convex shape or a rough shape. For example, the reflector 120 isformed along the shape of the concave portion 112, and has a structurewhere a concave groove is formed in its inside.

The reflector 120 may be formed of at least one of the reflectionmaterial group consisting of SiO₂, SiO_(x), SiN₂, SiN_(x), SiO_(x)N_(y)or metal materials (for example, tungsten). The reflector 120 may beformed of at least one of the semiconductor group consisting of GaN,InN, AlN, InGaN, AlGaN or InAlGaN and the reflection material group. Thereflector 120 may be formed in a single layer or multi layers by usingthe materials.

The first conductive semiconductor layer 130 is formed on the nitridesemiconductor layer 110. The first conductive semiconductor layer 130may be formed of at least one of the compound semiconductors of groupIII-V elements (on which a first conductive dopant is doped), forexample, GaN, AlN, AlGaN, InGaN, InN, InAlGaN and AlInN. In a case wherethe first conductive semiconductor layer 130 is an N-type semiconductorlayer, the first conductive dopant comprises an N-type dopant such asSi, Ge, Sn, Se and Te. The first conductive semiconductor layer 130 mayserve as an electrode contact layer, but is not limited thereto.

The first conductive semiconductor layer 130 may be formed of the samesemiconductor material as or a semiconductor material different fromthat of the nitride semiconductor layer 120. Herein, in a case where thenitride semiconductor layer 120 comprises a first conductive dopant, itmay be composed of a semiconductor having the first conductive dopant.

The sealed cavity 125 may be formed in at least one of the reflectors120. The cavity 125 may be formed in a certain shape between thereflector 120 and the first conductive semiconductor layer 130. Thecavity 125 may be formed in an inverse pyramid shape, an inversepolyhedron shape, an inverse horn shape or a plurality of irregularshapes at the inside of the inverse horn shape of the reflector 120. Thewidth or diameter of the cavity 125 is about 0.01 um to 10 um, and itsdepth is about 0.01 um to 10 um.

The active layer 140 is formed on the first conductive semiconductorlayer 130, and the active layer 140 may be formed in a single quantumwell structure or a multiple quantum well structure.

The active layer 140 may form the period of a well layer and a barrierlayer, for example, the period of an InGaN well layer/GaN barrier layeror the period of an AlGaN well layer/GaN barrier layer by using thecompound semiconductor material of group III and group V elements. Theactive layer 140 may be formed of a material having a bandgap energyaccording to the wavelength of an emitting light. The active layer 140may comprise a material that emits a chromatic light such as a lighthaving a blue wavelength, a light having a red wavelength and a lighthaving a green wavelength.

A conductive clad layer may be formed on and/or under the active layer140, and the conductive clad layer may be formed of an AlGaN-basedsemiconductor.

At least one second conductive semiconductor layer 150 is formed on theactive layer 140, and the second conductive semiconductor layer 150 maybe formed of at least one of the compound semiconductors of group III-Velements (on which a second conductive dopant is doped), for example,GaN, AlN, AlGaN, InGaN, InN, InAlGaN and AlInN. In a case where thesecond conductive semiconductor layer 150 is a P-type semiconductorlayer, the second conductive dopant may comprise a P-type dopant such asMg and Ze. The second conductive semiconductor layer 150 may serve as anelectrode contact layer, but is not limited thereto.

Herein, the first conductive semiconductor layer 130, the active layer140 and the second conductive semiconductor layer 150 may be defined asa light emitting structure. The first conductive semiconductor layer 130may be formed of a P-type semiconductor layer, and the second conductivesemiconductor layer 150 may be formed of an N-type semiconductor layer.Moreover, a third conductive semiconductor layer, for example, an N-typesemiconductor or a P-type semiconductor, may be formed on the secondconductive semiconductor layer 150. Accordingly, the light emittingstructure may comprise at least one of an N-P junction structure, a P-Njunction structure, an N-P-N junction structure and a P-N-P junctionstructure.

A first electrode is formed on the first conductive semiconductor layer130, and a second electrode 163 is formed on the second conductivesemiconductor layer 150.

An electrode layer (not shown), for example, a transparent electrodelayer or a reflection electrode layer may be formed on the secondconductive semiconductor layer 150. The second electrode 163 mayelectrically contact the electrode layer or/and the second conductivesemiconductor layer. The transparent electrode layer may be formed of atleast one of ITO, ZnO, RuOx, TiOx and IrOx, and the reflection electrodelayer may be formed of at least one of Al, Ag, Pd, Rh, Pt and Ir.

In the semiconductor light emitting device 100, when a power supplysource is applied through the first electrode 161 and the secondelectrode 163, light which is radiated by the active layer 140 isradiated in a forward direction. At this point, light traveling to thereflector 120 is reflected, refracted and diffused by the reflector 120,thereby changing the critical angle of the light. Moreover, the lightmay be reflected or refracted by the medium difference between thereflector 120, the cavity 125 and the first conductive semiconductorlayer 130. Accordingly, the semiconductor light emitting device 100decreases the total reflection rate of light in the inside of a device,thereby improving light extraction efficiency.

FIGS. 2 to 13 are diagrams illustrating a process of manufacturing thesemiconductor light emitting device in FIG. 1.

Referring to FIGS. 2 and 3, a mask layer 105A is formed on the substrate101. The substrate 101 may be formed of at least one of sapphiresubstrate (Al₂O₃), GaN, SiC, ZnO, Si, GaP and GaAs.

The mask layer 105A may be selected from the group consisting of SiO₂,SiO_(x), SiN₂, SiN_(x), and SiO_(x)N_(y). The mask layer 105A isdeposited in Plasma Enhanced Chemical Vapor Deposition (PECVD) orsputtering.

The mask layer 105A may be formed by selectively using photomaskmaterials such as SiO₂, SiO_(x), SiN_(x), SiO_(x)N_(y) and metalmaterials, or may be formed of at least one of compound semiconductormaterials such as GaN, InN, AlN, InGaN, AlGaN and InAlGaN. However, thematerials may be changed in the spirit and scope of embodiments.

The mask layer 105A may be formed in the island pattern 105 having awindow 106 by an etching process using a certain mask pattern. In theisland pattern 105, an island having a circle or polygon shape may beformed at regular intervals or irregular intervals. Such an island shapeand pattern may be modified in the spirit and scope of embodiments.

In a case where a buffer layer (not shown) or/and an undopedsemiconductor layer (not shown) is formed on the substrate 101, the masklayer 105A may be formed on the buffer layer or the undopedsemiconductor layer. The buffer layer may be implemented with a groupIII-V compound semiconductor for decreasing a lattice constant withrespect to the substrate 101. The undoped semiconductor layer may beimplemented with an undoped GaN-based semiconductor.

FIG. 4 is a diagram illustrating the plan view of FIG. 2. The islandpattern 105 is formed in a zigzag shape on the substrate 101.

Referring to FIGS. 5 and 6, the nitride semiconductor layer 110 isformed on the substrate 101 and the island pattern 105.

A nitride semiconductor grows on the substrate 101, and may grow bygrowth equipment such as electron beam evaporator, Physical VaporDeposition (PVD), Chemical Vapor Deposition (CVD), Plasma LaserDeposition (PLD), dual-type thermal evaporator, sputtering and MetalOrganic Chemical Vapor Deposition (MOCVD), but is not limited thereto.

When the nitride semiconductor layer 110 is GaN, it may be formed in CVD(or MOCVD). For example, the nitride semiconductor layer 110 may use agroup-III gas such as trimethyl gallium (TMGa) or triethyl gallium(TEGa) as a source gas for Ga, and may use a group-V gas such as ammonia(NH₃), monomethyl hydrazine (MMHy) or dimethyl hydrazine (DMHy) as asource gas for N.

By controlling growth conditions such as a growth temperature, a group-Vgas to group-III gas ratio and a growth pressure, the nitridesemiconductor layer 110 may grow. In this case, the nitridesemiconductor layer 110 grows from the top of the substrate 101 at theinitial stage of growth. As a growth time elapses, the nitridesemiconductor layer 110 grows to the top of the island pattern 105. Atthis point, the nitride semiconductor layer 110 may be sutured or maynot be sutured on the island pattern 105, but is not limited thereto.

A region corresponding to the island pattern 105 is the concave portion112 of the nitride semiconductor layer 110, and a region other than theconcave portion 112 is the convex portion 113 of the nitridesemiconductor layer 110.

The nitride semiconductor layer 110 may be selected from the groupconsisting of GaN, InN, AlN, InGaN, AlGaN and InAlGaN. Moreover, thenitride semiconductor layer 110 may be implemented with a semiconductorlayer on which a conductive dopant is doped or not. The concave portion112 of the nitride semiconductor layer 110 may be formed in an inversehorn shape such as an inverse pyramid shape, an inverse multi-angle hornshape and an inverse cone shape. For example, the concave portion 112 ofthe nitride semiconductor layer 110 may be formed in the inverse pyramidshape by the crystallinity of a GaN-based semiconductor.

In the concave portion 112 of the nitride semiconductor layer 110, itsdiameter D1 and depth D0 may be formed by semiconductor crystallization,or may be formed in consideration of the size of the reflector 120. Theconcave portions 112 of the nitride semiconductor layer 110 may beformed at constant intervals and of a conformal size, or may be formedat irregular intervals and of a random size.

Herein, the concave portion 112 of the nitride semiconductor layer 110may be formed without forming the island pattern 105, but may bemodified in the spirit and scope of embodiments.

FIG. 7 is a plan view of FIG. 6. The concave portion 112 of the nitridesemiconductor layer 110 may be formed in an inverse multi-angle hornshape at a position corresponding to the island pattern of FIG. 4.

Referring to FIGS. 7 and 8, a reflector layer 120A is formed on thenitride semiconductor layer 110. The reflector layer 120A may be formedin a single layer or multi layers. The reflector layer 120A may beformed of at least one of the reflection material group consisting ofSiO₂, SiO_(x), SiN₂, SiN_(x), SiO_(x)N_(y) or metal materials (forexample, tungsten). The reflector layer 120A may be formed in two ormore layers by selectively using the semiconductor group consisting ofGaN, InN, AlN, InGaN, AlGaN or InAlGaN and the reflection materialgroup.

The reflector layer 120A may be formed to a certain thickness T1 fromthe top of the nitride semiconductor layer 110.

The surface of the reflector layer 120A may be formed in aconcave-convex shape, and the concave shape may be formed in a shapecorresponding to the concave portion 112 of the nitride semiconductorlayer 110.

Referring to FIGS. 8 and 9, the certain thickness T1 of the reflectorlayer 120A is removed. The reflector layer 120A is removed until theconvex portion 113 of the nitride semiconductor layer 110 is exposed.The removing process is performed in a polishing process, a selectiveetching process or an etching process next to the polishing process. Ifthe reflector layer 120A is polished to the certain thickness T1, asillustrated in FIG. 8, a plurality of reflectors 120 exist in theconcave portions 112 of the nitride semiconductor layer 110,respectively. The plurality of reflectors 120 may be discontinuouslyarranged.

The reflector 120 may be formed in a concave-convex shape by the concaveshape of the reflector layer 120A. That is, the reflector 120 has aninverse multi-angle horn shape, and a groove 120B having a concave shapemay be formed in the inside of the reflector 120.

Herein, the upper side of the nitride semiconductor layer 110 iscomposed of the concave portions 112 and the convex portions 113. Theeach concave portion 112 is formed in such a form that it accommodatesthe each reflector 120. The plurality of reflectors 120 are spacedapart, and are disposed in a position corresponding to the islandpattern 105.

Moreover, the size and shape of the reflector 120 is determined by theconcave shape of the nitride semiconductor layer 110, or may be modifiedaccording to a polishing or etching rate. The size and shape of thereflector 120 may be modified in the spirit and scope of embodiments.

Referring to FIG. 10, the reflector 120 which is formed on the concaveportion 112 of the nitride semiconductor layer 110 may be formed in ashape corresponding to that of the concave portion 112, for example, aninverse cone shape or an inverse multi-angle horn shape. Alternatively,the reflector 120 may be formed in other shapes, for example, aconcave-convex shape or a rough shape. The shape of the reflector 120may be modified.

Referring to FIGS. 9 and 11, the first conductive semiconductor layer130 may be formed on the nitride semiconductor layer 110. The firstconductive semiconductor layer 130 may be formed of at least one of thecompound semiconductors of group III-V elements (on which a firstconductive dopant is doped), for example, GaN, AlN, AlGaN, InGaN, InN,InAlGaN and AlInN. In a case where the first conductive semiconductorlayer 130 is an N-type semiconductor layer, the first conductive dopantcomprises an N-type dopant such as Si, Ge, Sn, Se and Te.

In a case where the growth temperature of the first conductivesemiconductor layer 130 can gradually increase, a lateral growth may bepromoted and a flat top may be formed, but is not limited thereto.

Herein, the first conductive semiconductor layer 130 may be formed onthe reflectors 120. At this point, the cavity 125 which is not filledwith the first conductive semiconductor layer 130 may be formed in atleast one of the reflectors 120. The cavity 125 may be formed with asealed structure between the reflector 120 and the first conductivesemiconductor layer 130. In the size of the cavity 125, a diameter D2may be formed to about 0.01 um to 10 um, and a depth T2 may be formed toabout 0.01 um to 10 um.

The shape of the cavity 125 may be formed in an inverse horn shape suchas an inverse cone shape or an inverse multi-angle horn shape, or may beformed in a constant or random shape.

Herein, the reflectors 120, the cavities 125 and the first conductivesemiconductor layer 130 are disposed with different mediums, and thus,the reflectors 120 and the cavities 125 may reflect, refract and diffuselight which is incident through the first conductive semiconductor layer130.

The refraction index of the first conductive semiconductor layer 130 isabout 2.12 to 2.44, and the refraction index of the cavity 125 isabout 1. When the reflector 120 is formed of SiO₂, its refraction indexis about 1.544 to 1.553. By reflecting light incident to the mediums,the critical angle of traveling light can be changed. Moreover, thecavity 125 and the reflector 120 decrease the internal total reflectionrate of light, thereby improving light extraction efficiency.

Referring to FIG. 12, the active layer 140 may be -formed on the firstconductive semiconductor layer 130. The active layer 140 is formed in asingle quantum well structure or a multiple quantum well structure. Theactive layer 140 may comprise a material that emits a chromatic lightsuch as a light having a blue wavelength, a light having a redwavelength and a light having a green wavelength. A conductive cladlayer may be formed on or/and under the active layer 140, and theconductive clad layer may be formed in an AlGaN-based semiconductor.

The second conductive semiconductor layer 150 is formed on the activelayer 140. The second conductive semiconductor layer 150 may be formedof at least one of the compound semiconductors of group III-V elements(on which a second conductive dopant is doped), for example, GaN, AlN,AlGaN, InGaN, InN, InAlGaN and AlInN. In a case where the secondconductive semiconductor layer 150 is a P-type semiconductor layer, thesecond conductive dopant may comprise a P-type dopant such as Mg and Ze.

The third conductive semiconductor layer, for example, an N-typesemiconductor layer or a P-type semiconductor layer, may be formed onthe second conductive semiconductor layer 150. Accordingly, a lightemitting structure may comprise at least one of an N-P junctionstructure, a P-N junction structure, an N-P-N junction structure and aP-N-P junction structure.

Referring to FIGS. 12 and 13, a mesa etching process is performed. Themesa etching process is performed until the first conductivesemiconductor layer 130 is exposed. The first electrode 161 may beformed on the first conductive semiconductor layer 130, and the secondelectrode 163 may be formed on the second conductive semiconductor layer150.

Herein, an electrode layer (not shown) may be formed on the secondconductive semiconductor layer 150. The electrode layer may be formedbefore or after the mesa etching process, and may be formed as atransparent electrode layer or a reflection electrode layer. Thetransparent electrode layer may be formed of at least one of ITO, ZnO,RuOx, TiOx and IrOx, and the reflection electrode layer may be formed ofat least one of Al, Ag, Pd, Rh, Pt and Ir. The second electrode 163 mayelectrically contact the second conductive semiconductor layer 150and/or the electrode layer.

The second electrode 163 or the electrode layer (not shown)/secondelectrode may be defined as a second electrode portion. Moreover, thesurfaces of the second conductive semiconductor layer 150 and theelectrode layer may be formed in a roughness shape, but is not limitedthereto.

FIG. 14 is a diagram illustrating a semiconductor light emitting deviceaccording to a second embodiment. In description of the secondembodiment, repetitive description on the same elements as those of thefirst embodiment will be omitted and refers to that of the firstembodiment.

Referring to FIG. 14, a semiconductor light emitting device 100Aaccording to the second embodiment comprises a first conductive nitridesemiconductor layer 110, a first electrode 161A, the reflector 120, thecavity 125, the first conductive semiconductor layer 130, the activelayer 140, the second conductive semiconductor layer 150, and a secondelectrode portion 170.

The second electrode portion 170 is formed on the second conductivesemiconductor layer 150, and comprises the stacked structure of aconductive support member and a reflection electrode layer (not shown).The reflection electrode layer is formed on the second conductivesemiconductor layer 150, and may be formed of at least one of Al, Ag,Pd, Rh, Pt and Ir. The conductive support member may be formed of atleast one of copper, gold and carrier wafer (for example, Si, Ge, GaAs,ZnO, SiC and the like) on the reflection electrode layer.

Herein, the substrate 101 is removed from the structure of FIG. 12. Thesubstrate 101 may be removed in a physical/chemical process. Thephysical process, for example, may remove the substrate 101 in a LaserLift Off (LLO) process using a laser.

When the substrate 101 is removed, the island pattern 105 may be removedor not.

Furthermore, the first electrode 161A is formed under the nitridesemiconductor layer 110. The nitride semiconductor layer 110 is asemiconductor on which a first conductive dopant is doped, or may beimplemented with the first conductive semiconductor layer 130.Accordingly, a power supply source which is injected through the firstelectrode 161A is transferred to the first conductive semiconductorlayer 130 through the nitride semiconductor layer 110.

Light which is radiated from the active layer 140 is reflected by theelectrode member 170, and the reflector 120 and/or the cavity 125reflects, refracts and diffuses the light, thereby changing the criticalangle of the light.

FIGS. 15 to 21 are diagrams illustrating a semiconductor light emittingdevice according to a third embodiment. In description of the thirdembodiment, repetitive description on the same elements as those of thefirst embodiment will be omitted and refers to that of the firstembodiment.

Referring to FIGS. 15 and 16, a mask layer 105A is formed on thesubstrate 101. The mask layer 105A may be formed by selectively usingphotomask materials such as SiO₂, SiO_(x), SiN_(x), SiO_(x)N_(y) andmetal materials, or may be formed of at least one of compoundsemiconductor materials such as GaN, InN, AlN, InGaN, AlGaN and InAlGaN.However, the materials may be changed in the spirit and scope ofembodiments.

The mask layer 105A may be formed in the island pattern 105 having thewindow 106 by an etching process using a certain mask pattern. In theisland pattern 105, an island having a circle or polygon shape may beformed at regular intervals or irregular intervals. Such an island shapeand pattern may be modified in the spirit and scope of embodiments.

Referring to FIGS. 16 and 17, the nitride semiconductor layer 110 isformed on the substrate 101 and the island pattern 105. When the nitridesemiconductor layer 110 is GaN, it may be formed in CVD (or MOCVD). Forexample, the nitride semiconductor layer 110 may use a group-III gassuch as trimethyl gallium (TMGa) or triethyl gallium (TEGa) as a sourcegas for Ga, and may use a group-V gas such as ammonia (NH₃), monomethylhydrazine (MMHy) or dimethyl hydrazine (DMHy) as a source gas for N.

By controlling growth conditions such as a growth temperature, a group-Vgas to group-III gas ratio and a growth pressure, the nitridesemiconductor layer 110 may grow. In this case, the nitridesemiconductor layer 110 grows from the top of the substrate 101 at theinitial stage of growth. As a growth time elapses, the nitridesemiconductor layer 110 grows to the top of the island pattern 105. Atthis point, the nitride semiconductor layer 110 may be sutured or maynot be sutured on the island pattern 105, but is not limited thereto.

A region corresponding to the island pattern 105 is the concave portion112 of the nitride semiconductor layer 110, and a region other than theconcave portion 112 is the convex portion 113 of the nitridesemiconductor layer 110.

The nitride semiconductor layer 110 may be selected from the groupconsisting of GaN, InN, AlN, InGaN, AlGaN and InAlGaN. Moreover, thenitride semiconductor layer 110 may be implemented with a semiconductorlayer on which a conductive dopant is doped or not. The concave portion112 of the nitride semiconductor layer 110 may be formed in an inversehorn shape such as an inverse pyramid shape, an inverse multi-angle hornshape and an inverse cone shape. For example, the concave portion 112 ofthe nitride semiconductor layer 110 may be formed in the inverse pyramidshape by the crystallinity of a GaN-based semiconductor.

In the concave portion 112 of the nitride semiconductor layer 110, itsdiameter D3 and depth D4 may be formed by semiconductor crystallization,or may be formed in consideration of the size of the reflector 120. Theconcave portions 112 of the nitride semiconductor layer 110 may beformed at constant intervals and of a conformal size, or may be formedat irregular intervals and of a random size.

Referring to FIGS. 17 and 18, a reflector layer 121A is formed on thenitride semiconductor layer 110. The reflector layer 121A may be formedin a single layer or multi layers. The reflector layer 121A may beformed of at least one of the reflection material group consisting ofSiO₂, SiO_(x), SiN₂, SiN_(x), SiO_(x)N_(y) or metal materials (forexample, tungsten). The reflector layer 121A may be formed in two ormore layers by selectively using the semiconductor group consisting ofGaN, InN, AlN, InGaN, AlGaN or InAlGaN and the reflection materialgroup.

The reflector layer 121A may be formed to a certain thickness T3 alongthe concave portion 112 and convex portion 113 of the nitridesemiconductor layer 110. Herein, the depth of the groove 121B of thereflector layer 121A may be formed to the region of the concave portion112 of the nitride semiconductor layer 110.

The shape of the groove 121B of the reflector layer 121A may be formedin a shape corresponding to the concave portion 112 of the nitridesemiconductor layer 110.

Referring to FIGS. 18 and 19, the certain thickness T3 of the reflectorlayer 121A is removed. The reflector layer 121A is removed until theconvex portion 113 of the nitride semiconductor layer 110 is exposed.The removing process is performed in a polishing process, a selectiveetching process or an etching process next to the polishing process. Ifthe reflector layer 121A is polished to the certain thickness T3, asillustrated in FIG. 19, a plurality of reflectors 121 exist in theconcave portions 112 of the nitride semiconductor layer 110,respectively. The plurality of reflectors 121 may be discontinuouslyarranged.

The reflector 121 may be formed in a concave-convex shape (for example,a cross-sectional surface having a V shape) by the concave shape of thereflector layer 120A. That is, the reflector 121 has an inversemulti-angle horn shape, and a groove 121B having a concave shape may beformed in the inside of the reflector 120. The groove 121B of thereflector 121 may be formed to have a width narrower than that of thegroove 120B of the reflector 120 according to the first embodiment, andmay be formed to have a depth deeper than that of the groove 120B of thereflector 120 according to the first embodiment.

Referring to FIGS. 19 to 21, the first conductive semiconductor layer130 is formed on the nitride semiconductor layer 110. The firstconductive semiconductor layer 130 grows through the nitridesemiconductor layer 110. In the growth of the first conductivesemiconductor layer 130, a lateral growth is promoted as a growth timeelapses, and thus it is extended and grown to the top of the reflector121. The first conductive semiconductor layer 130 may be sutured on thereflector 121, and the region of the groove 121B of the reflector 121may be formed as the cavity 125 as illustrated in FIG. 21. The cavity125 may be formed in the each reflector 121, but is limited thereto.

The active layer 140 and the second conductive semiconductor layer 150may be formed on the first conductive semiconductor layer 130. The firstconductive semiconductor layer 130, the active layer 140 and the secondconductive semiconductor layer 150 refer to the first embodiment.

In the semiconductor light emitting device 100B, the cavity 125 isformed in each of the plurality of reflectors 121. Accordingly, thereflectors 121, the cavities 125 and the first conductive semiconductorlayer 130 may reflect, refract and diffuse light, thereby improving thelight extraction efficiency of the semiconductor light emitting device100B.

The semiconductor light emitting device 100B may be manufactured as thelateral semiconductor light emitting device of FIG. 13, or may bemanufactured as the vertical semiconductor light emitting device of FIG.14.

FIGS. 22 to 28 are diagrams illustrating a process of manufacturing asemiconductor light emitting device according to a fourth embodiment. Indescription of the fourth embodiment, repetitive description on the sameelements as those of the first embodiment will be omitted and refers tothat of the first embodiment.

Referring to FIGS. 22 and 23, the mask layer 105A is formed on thesubstrate 101. The mask layer 105A may be formed by selectively usingphotomask materials such as SiO₂, SiO_(x), SiN_(x), SiO_(x)N_(y) andmetal materials, or may be formed of at least one of compoundsemiconductor materials such as GaN, InN, AlN, InGaN, AlGaN and InAlGaN.However, the materials may be changed in the spirit and scope ofembodiments.

The mask layer 105A may be formed in the island pattern 105 having thewindow 106 by an etching process using a certain mask pattern. In theisland pattern 105, an island having a circle or polygon shape may beformed at regular intervals or irregular intervals. Such an island shapeand pattern may be modified in the spirit and scope of embodiments.

Referring to FIGS. 23 and 24, the nitride semiconductor layer 110 isformed on the substrate 101 and the island pattern 105. By controllinggrowth conditions such as a growth temperature, a group-V gas togroup-III gas ratio and a growth pressure, the nitride semiconductorlayer 110 may grow. In this case, the nitride semiconductor layer 110grows from the top of the substrate 101 at the initial stage of growth.As a growth time elapses, the nitride semiconductor layer 110 grows tothe top of the island pattern 105. At this point, the nitridesemiconductor layer 110 may be sutured or may not be sutured on theisland pattern 105, but is not limited thereto.

A region corresponding to the island pattern 105 is the concave portion112 of the nitride semiconductor layer 110, and a region other than theconcave portion 112 is the convex portion 113 of the nitridesemiconductor layer 110.

The nitride semiconductor layer 110 may be selected from the groupconsisting of GaN, InN, AlN, InGaN, AlGaN and InAlGaN. Moreover, thenitride semiconductor layer 110 may be implemented with a semiconductorlayer on which a conductive dopant is doped or not. The concave portion112 of the nitride semiconductor layer 110 may be formed in an inversehorn shape such as an inverse pyramid shape, an inverse multi-angle hornshape and an inverse cone shape. Moreover, the concave portions 112 ofthe nitride semiconductor layer 110 may be formed at constant intervalsand of a conformal size, or may be formed at irregular intervals and ofa random size.

Referring to FIGS. 24 and 25, a reflector layer 122A is formed on thenitride semiconductor layer 110. The reflector layer 122A may be formedin a single layer or multi layers. The reflector layer 122A may beformed of at least one of the reflection material group consisting ofSiO₂, SiO_(x), SiN₂, SiN_(x), SiO_(x)N_(y) or metal materials (forexample, tungsten). The reflector layer 122A may be formed in two ormore layers by selectively using the semiconductor group consisting ofGaN, InN, AlN, InGaN, AlGaN or InAlGaN and the reflection materialgroup.

The reflector layer 122A may be formed to a certain thickness along theconcave portion 112 and convex portion 113 of the nitride semiconductorlayer 110. Herein, the depth of the groove 122B of the reflector layer122A may be formed to the extended line of the concave portion 112 ofthe nitride semiconductor layer 110.

The shape of the groove 122B of the reflector layer 122A may be formedin a shape corresponding to the concave portion 112 of the nitridesemiconductor layer 110.

Referring to FIGS. 25 and 26, the reflector layer 122A is removed untilthe top of the nitride semiconductor layer 110 is exposed. The removingprocess is performed in a polishing process, a selective etching processor an etching process next to the polishing process. If the reflectorlayer 122A is polished, as illustrated in FIG. 26, a plurality ofreflectors 122 exist in the concave portions 112 of the nitridesemiconductor layer 110, respectively. The plurality of reflectors 122are discontinuously arranged in a structure.

The reflector 122 may be formed in an inverse multi-angle horn shapewith no internal concave groove. The top of the reflector 122 and thetop of the nitride semiconductor layer 110 may be on the same straightline.

Referring to FIGS. 27 and 28, the first conductive semiconductor layer130 is formed on the nitride semiconductor layer 110. The firstconductive semiconductor layer 130 grows through the nitridesemiconductor layer 110. As a growth time elapses, the first conductivesemiconductor layer 130 is extended and grown to the top of thereflector 122. Subsequently, a lateral growth is promoted by controllingthe growth temperature of the nitride semiconductor layer 110, and thus,the first conductive semiconductor layer 130 is sutured with thereflector 121 so that a flat top may be formed. Herein, a cavity may notbe formed between the reflector 122 and the first conductivesemiconductor layer 130.

The active layer 140 and the second conductive semiconductor layer 150may be formed on the first conductive semiconductor layer 130. The firstconductive semiconductor layer 130, the active layer 140 and the secondconductive semiconductor layer 150 refer to the first embodiment.

A semiconductor light emitting device 100C according to the fourthembodiment may reflect, refract and diffuse light by the plurality ofreflectors 122 and the first conductive semiconductor layer 130, therebyimproving light extraction efficiency thereof.

The semiconductor light emitting device 100C may be manufactured as thelateral semiconductor light emitting device of FIG. 13, or may bemanufactured as the vertical semiconductor light emitting device of FIG.14.

FIG. 29 is a side-sectional view of a semiconductor light emittingdevice according to a fifth embodiment. In description of the fifthembodiment, repetitive description on the same elements as those of thefirst embodiment will be omitted and refers to that of the firstembodiment.

Referring to FIG. 29, a semiconductor light emitting device 100Daccording to the fifth embodiment comprises an island pattern 105Bformed of irregular sizes and at irregular intervals on the substrate110.

The island pattern 105B is formed in an island shape by controlling thethin-film growth conditions of a compound semiconductor. The islandpattern 105B may be selected from the group consisting of GaN, InN, AlN,InGaN, AlGaN and InAlGaN, but is not limited thereto.

The island pattern 105B, for example, may be formed in an island shapeby using a GaN crystal having a hexagonal crystal structure on thesubstrate 101. The island shape of the island pattern 105B may be formedto have a cross-sectional surface of a trapezoid shape and a randomsize.

The following description will be made in detail on a process ofmanufacturing the island pattern 105B.

First, a growth temperature is controlled at an initial temperature (C1)of a first stage in the reaction chamber of growth equipment (forexample, MOCVD), and the GaN seed layer of a compound semiconductorgrows by providing an atmosphere gas, a Ga source gas and an N sourcegas. Herein, the GaN seed layer may be formed as a GaN buffer layer or aGaN core formation layer.

Subsequently, the growth temperature increases at the growth temperature(C2) of a second stage, and thus, the GaN seed layer grows in an islandshape. In the island pattern 105B, for example, a GaN semiconductor seedmay grow for three minutes at 530C in the first stage, and may grow forone minute at 1050C in the second stage. Herein, hydrogen (H₂) andnitrogen (N₂) are provided as the atmosphere gas, ammonia (NH₃) isprovided as the N source gas, and trimethyl gallium (TMGa) is providedas the Ga source gas. The growth temperature (C1) of the first stage isabout 300° C. to 900° C., and the growth temperature (C2) of the secondstage is about 700° C. to 1200° C.

Moreover, the island pattern 105B may grow in such a form that a lateralsurface parallel to the surface of the substrate 101 does not almostexist.

In the growth of the island pattern 105B, the growth temperatures (C1and C2) may be changed at several stages with time, and may becontinuously changed from the growth temperature (C1) of the first stageto the growth temperature (C2) of the second stage with time.Alternatively, the growth of the island pattern 105B is separatelyperformed at several sections. In this case, the growth stops and anannealing process may be performed between the respective sections, orthe growth temperature of the each section may be maintained for acertain time. Alternatively, the growth temperature mayincrease/decrease and the press of the reaction chamber may becontrolled under growth. In addition, by controlling the change of thegrowth temperature with time, a semiconductor having irregularthree-dimensional island shapes may be formed.

The island pattern 105B may be formed to a thickness of 100 Å to 1 um,and may serve as a buffer layer on the substrate 101.

A nitride semiconductor layer 110A is formed on the island pattern 105B.The nitride semiconductor layer 110A grows on the island shape of theisland pattern 105B, and thus, its surface may be formed in the shapesof the concave portion 112 and the convex portion 113. The nitridesemiconductor layer 110A may be selected from the group consisting ofGaN, InN, AlN, InGaN, AlGaN and InAlGaN, and may also be formed as asemiconductor layer on which a conductive dopant is doped or an undopedsemiconductor layer on which the conductive dopant is not doped.

The concave portions 112 of the nitride semiconductor layer 110A may beformed of a non-conformal size and at irregular intervals due to thenon-conformal size or irregular arrangement of the island pattern 105B.

A plurality of reflectors 123 are formed on the concave portions 112 ofthe nitride semiconductor layer 110A respectively, and may be formed ofa non-conformal size and in a non-conformal shape. The cavity 125 may beformed in at least one of the reflectors 123. Herein, the plurality ofcavities 125 may differ from one another according to the sizes of therespective reflectors 123.

The lateral structure of the semiconductor light emitting device 100Dhas been described above, but the semiconductor light emitting device100D may be manufactured in a vertical structure.

The semiconductor light emitting device 100D can improve lightextraction efficiency by the non-conformal sizes of the reflectors 123and the cavities 125.

FIG. 30 is a diagram illustrating a semiconductor light emitting deviceaccording to a sixth embodiment. In description of the sixth embodiment,repetitive description on the same elements as those of the first andfifth embodiments will be omitted and refers to that of the first andfifth embodiments.

Referring to FIG. 30, a semiconductor light emitting device 100Eaccording to the sixth embodiment comprises a plurality of reflectors124 composed of multi-layer reflectors 124A, 124B and 124C.

The reflector 124 may be implemented as the multi-layer reflectors 124A,124B and 124C on the each concave portion 112 of the nitridesemiconductor layer 110A.

The first reflector 124A of the reflector 124 is stacked on the concaveportion 112 of the nitride semiconductor layer 110A, the secondreflector 124B is stacked on the first reflector 124A, and the thirdreflector 124C is stacked on the second reflector 124B.

In the reflector 124, the first and second reflectors 124A and 124B maybe implemented as a pair or multi pairs. The first reflector 124A may beselected from the group consisting of SiO₂, SiO_(x), SiN₂, SiN_(x),SiO_(x)N_(y) or metal materials (for example, tungsten). Herein, thefirst reflectors 124A may be discontinuously formed in a concave-convexstructure having an inverse horn shape.

The second reflector 124B may be selected from the group consisting ofGaN, InN, AlN, InGaN, AlGaN or InAlGaN, or may be selected from thegroup consisting of materials different from the first reflector 124A,for example, SiO₂, SiO_(x), SiN₂, SiN_(x), SiO_(x)N_(y) or metalmaterials.

The uppermost third reflector 124C of the reflector 124 is formed of afirst reflection material, or may be formed of a semiconductor differentfrom the first conductive semiconductor layer 130. Moreover, the thirdreflector 124C may be formed in an arbitrary geometrical shape such aspolyhedron and a curved figure instead of a layer shape, or may beformed of particles having a certain size. The reflector 124 mayprotrude to the inside of the first conductive semiconductor layer 130.

The reflector 124 grows as a reflector layer having a multi-layerstructure. Subsequently, only the structure of the reflector 124remains, and the reflector 124 is etched in a selective etching process(for example, a wet etching process and a dry etching process). Thereflectors 124 may be discontinuously disposed in the etching process.

The multi-layer reflectors 124A, 124B and 124C may be implemented withat least one of a hetero-joined reflector, a periodically hetero-joinedsuper lattice structure, a hetero reflector having no period and aDistributed-Bragg Reflector (DBR) structure.

At least one of the cavities 125 may be formed between the reflector 124and the first conductive semiconductor layer 130. The first conductivesemiconductor layer 130, the reflector 124 or/and the cavity 125 mayeffectively change the path of incident light. Although the lateralstructure of the semiconductor light emitting device 100E has beendescribed above, the semiconductor light emitting device 100E may bemanufactured in a vertical structure, but is not limited thereto.

The structure of the reflector according to the above-disclosedembodiments may be formed in regular or irregular concave-convex shapesin the lower portion of the light emitting structure. Moreover, thecavity is formed in at least one of the plurality of reflectors, therebyreflecting, diffusing, diffracting or/and refracting light which travelsby the refraction index and geometrical features of the reflector andthe cavity. Accordingly, the total reflection rate of light may decreaseand light extraction efficiency may be improved in the inside of thesemiconductor light emitting device. Moreover, The technicalcharacteristics of the above-disclosed embodiments are not limitedthereto, and may be selectively applied to another embodiment.

Although the embodiment has been made in relation to the compoundsemiconductor light emitting device comprising the N-P junctionstructure as an example, the compound semiconductor light emittingdevice comprising an N-P-N structure, a P-N structure or a P-N-Pstructure can be implemented. In the description of the embodiment, itwill be understood that, when a layer(or film), a region, a pattern, ora structure is referred to as being “on(above/over/upper)” or“under(below/down/lower)” another substrate, another layer(or film),another region, another pad, or another pattern, it can be directly onthe other substrate, layer (or film), region, pad or pattern, orintervening layers may also be present. Furthermore, it will beunderstood that, when a layer (or film), a region, a pattern, a pad, ora structure is referred to as being “between” two layers (or films),regions, pads or patterns, it can be the only layer between the twolayers (or films), regions, pads, or patterns or one or more interveninglayers may also be present. Thus, it should be determined by technicalidea of the invention.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is comprised in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A semiconductor light emitting device, comprising: a first nitridesemiconductor layer comprising a plurality of concave portions; areflector in at least one of the concave portions of the first nitridesemiconductor layer; and a second nitride semiconductor layer on thefirst nitride semiconductor layer.
 2. The semiconductor light emittingdevice according to claim 1, comprising at least one cavity between thereflector and the second nitride semiconductor layer.
 3. Thesemiconductor light emitting device according to claim 1, comprising atleast one of an undoped semiconductor layer, a buffer layer, a substrateand a first electrode under the first nitride semiconductor layer. 4.The semiconductor light emitting device according to claim 1,comprising: an active layer on the second nitride semiconductor layer; asecond conductive semiconductor layer on the active layer; and a secondelectrode portion on the second conductive semiconductor layer.
 5. Thesemiconductor light emitting device according to claim 1, comprising: asubstrate under the first nitride semiconductor layer; and apredetermination pattern corresponding to the concave portions of thefirst nitride semiconductor layer on the substrate.
 6. The semiconductorlight emitting device according to claim 5, wherein the patterncomprises at least one of SiO_(2,) SiO_(x), SiN_(x), SiO_(x)N_(y), GaN,InN, AlN, InGaN, AlGaN, InAlGaN and a metal material.
 7. Thesemiconductor light emitting device according to claim 1, wherein thereflector comprises at least one of SiO₂, SiO_(x), SiN_(x),SiO_(x)N_(y), a metal material and a group III-V compound semiconductor.8. The semiconductor light emitting device according to claim 1, whereinthe reflector comprises at least one of a hetero-joined reflector, aperiodically hetero-joined super lattice structure, a hetero reflectorhaving no period and a Distributed-Bragg Reflector (DBR) structure. 9.The semiconductor light emitting device according to claim 2, whereinthe reflector or the cavity comprises an inverse cone shape or aninverse multi-angle horn shape.
 10. The semiconductor light emittingdevice according to claim 1, wherein the plurality of reflectors haveregular or irregular intervals and are formed to be accommodated in therespective concave portions.
 11. A semiconductor light emitting device,comprising: a nitride semiconductor layer comprising a plurality ofconcave portions; a plurality of reflectors in a plurality of theconcave portions of the nitride semiconductor layer; a cavity on atleast one of the reflectors; and a plurality of compound semiconductorlayers on the nitride semiconductor layer.
 12. The semiconductor lightemitting device according to claim 11, wherein the reflector is selectedfrom a group consisting of SiO_(2,) SiO_(x), SiN_(x), SiO_(x)N_(y) ormetal material in the concave portion of the nitride semiconductorlayer.
 13. The semiconductor light emitting device according to claim11, wherein the reflector comprises a single reflector or multireflectors having a pair structure of a hetero semiconductor among GaN,InN, AlN, InGaN, AlGaN and InAlGaN.
 14. The semiconductor light emittingdevice according to claim 11, wherein a diameter of the cavity is about0.Olum to 10 um, and a depth of the cavity is about 0.01 um to 10 um.15. The semiconductor light emitting device according to claim 11,comprising: a substrate under the nitride semiconductor layer; and aplurality of island patterns corresponding to the concave portions ofthe nitride semiconductor layer on the substrate, wherein the islandpattern comprises at least one of SiO₂, SiO_(x), SiN_(x), SiO_(x)N_(y),metal material and a compound semiconductor.
 16. The semiconductor lightemitting device according to claim 11, wherein the nitride semiconductorlayer comprises a semiconductor on which a first conductive dopant isdoped or an undoped semiconductor.
 17. The semiconductor light emittingdevice according to claim 11, wherein the concave portion of the nitridesemiconductor layer and the reflector comprise an inverse horn shape.18. A semiconductor light emitting device, comprising: a nitridesemiconductor layer comprising a plurality of concave portions having ahorn shape; a plurality of reflectors having a horn shape in theplurality of concave portions of the nitride semiconductor layer; and afirst conductive semiconductor layer on the nitride semiconductor layer.19. The semiconductor light emitting device according to claim 18,comprising at least one cavity formed with a horn shape between thefirst conductive semiconductor layer and the reflector.
 20. Thesemiconductor light emitting device according to claim 19, wherein thereflector has a horn shape where each layer is irregular, and comprisesa multi-layer reflector where a plurality of reflection materials ishetero-joined.